Purchasing MyTEAM packs with VC (Virtual Currency) is restricted in certain regions, like Belgium, Brazil, and South Korea. If your account is associated with those regions, these restrictions will apply.
Keep in mind that in these regions you can still acquire MyTEAM packs with MTPs (MyTEAM Points) and open free packs. The only restriction is using VC to purchase MyTEAM packs.
In case you're not in these regions and are having an issue purchasing the packs, feel free to reach out to our 2K Support Team. Be sure to include any error messages you're receiving to help us find any problems.